US Patent 8675875 Optimizing use of hardware security modules

Use of cryptographic key-store hardware security modules is optimized in a system having a first scarce high-security key storage device and a second more plentiful low-security key storage device comprising securing a cryptographic key to the higher security level by initially storing the key in the first storage device, then responsive to an event, evaluating the stored key against one or more rules, and subsequent to the evaluation, reclassifying the stored key for relocation, encrypting the reclassified key using a key-encryption key; relocating the reclassified key into the second, lower-security storage device, and storing the key-encryption key in the first storage device.